


Catachresis

by corbaccio



Category: Shingeki no Kyojin | Attack on Titan
Genre: Anal Sex, Consensual Mind Control, Dom/sub Undertones, Inappropriate Use of the Coordinate, M/M, Plot What Plot/Porn Without Plot
Language: English
Status: Completed
Published: 2020-10-12
Updated: 2020-10-12
Packaged: 2021-03-07 22:41:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,657
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26961574
Author URL: https://archiveofourown.org/users/corbaccio/pseuds/corbaccio
Summary: Hanji’s experiments with Eren’s coordinate power had been perfectly sound, perfectly innocent. It was just that they had unintended—unexpected—consequences, albeit ones that had taken a little while longer to manifest in Armin’s imagination.(In which Eren tries out his coordinate ability on Armin in rather more intimate circumstances.)
Relationships: Armin Arlert/Eren Yeager
Comments: 14
Kudos: 292





	Catachresis

**Author's Note:**

> i can't even be ashamed. please be aware of the tags, though everything is completely consensual, and eren's coordinate controls armin's body rather than his mind. (i take some serious liberties with how the coordinate works. but this is smut and i don't care.)

It’s hard to hear what Eren says with his mouth pressed against his collar. All Armin can make out is a mumble, and even then just the unhappy noise of it.

“What was that?”

Eren’s gaze swivels up from Armin’s shoulder to his face. He sounds almost sullen when he speaks, though he laces their fingers together in a fidgety tangle. “I didn’t say anything.” There’s a pause that Armin doesn’t disturb; he can recognise that Eren is not yet finished, and he knows better than to probe too much, too early.

It pours out of Eren in a rush.

“I know you said you wanted this. And I, I do too… It’s just, I’m worried I might hurt you or something.”

Armin settles back on the bed to take in Eren’s expression. A pinched frown, his mouth tight with uneasy misery. With new space between them, he reaches for Eren’s other hand to hold them both in his own. Armin strokes his knuckles, his tender palms, tracing the seam of Eren's lifeline with his thumb.

“I’d say something if I wasn’t comfortable,” Armin tells him. He leans their foreheads together in what's meant to be a reassuring touch, but when he feels Eren pull away, panic sparks in his chest. He hurries to speak. “I don’t want you to be uncomfortable either, Eren. We don’t have to do this if you don’t want to.”

Another beat passes. Then the warmth is back at his collar again. Eren rests his chin on his shoulder, his sigh opening up into a kiss, and Armin feels the familiar curve of a smile against the skin of his throat. His worry evaporates.

“I trust you, too,” Eren says softly. There’s an underlying heat in his voice that makes Armin shiver. Eren lifts his head to look him in the eye, and after a deep breath he goes on, “If you want to stop, just say the word and I will. Straight away.” He waits for Armin to nod, his stare unblinking, deliberate. “Okay. You ready?”

Armin’s insides give a pleasant little tug. If he were being honest, he’s been ready—been wanting this—for a long time now. He wants and trusts Eren in equal measure. The idea of surrendering to him so completely floods Armin with some unspeakable feeling, affection twisted up with trepidation.

“Yes. I’m ready.”

For a moment, him and Eren are still, as if expecting a shift in the universe at their agreement. But no, the room is still and silent around them, sat together on the edge of Armin’s bed. This is within their control. Armin lets that thought ease his remaining nerves. Eren is still slow to react, though, and Armin knows how to read him, how to soothe him. He holds Eren’s anxious gaze until his frown smooths away.

“Alright. First, uh, lie down,” Eren says, watchful as Armin sinks back into the mattress.

It doesn’t feel _that_ strange. Armin would have done it anyway had Eren asked, coordinate or not, but it does feel… different. Reflexive. A reaction he doesn’t quite control. He had barely registered Eren’s words before he was following them.

“Do you think I could…” Armin begins, trailing off at Eren’s raised eyebrow before ploughing on. If he hesitates now, they’ll lose their momentum. “Could I resist it, if I tried to?”

Eren looks thoughtful. Armin’s pragmatic manner, as if this were a simply a training exercise rather than—well, whatever this is—seems to relax him. His voice is even, at ease. “I don’t know. I mean, if I didn’t let up, then, well. Probably not.”

“Is it alright if I do try?” Armin asks.

This time Eren’s eyebrows disappear beneath his hair. He makes a quiet noise of disbelief. “You’re the one who’s letting me… you know. I don’t mind. As long as you’re okay with it.”

“I’m okay with it,” Armin says, quicker and more eager than he means to. It's much more difficult to hide his excitement than it was his unease. “I don’t want you to hold back. Just. Use as much force as you can.”

The hitch in Eren’s breathing is audible in the hushed stillness, his eyes going wide. He stares at Armin a moment, owlish, but then he’s nodding, settling back into his calm. Yes, they’re still okay.

The surprise must make Eren’s concentration lapse, because at first Armin feels no resistance at all when he sits up. Then, just as quickly, he’s falling back, like a mechanism set in sudden reverse. The mattress squeaks, but it isn’t so much the impact that knocks the breath out of him as the shock. He blinks dumbly up at Eren, amazed.

Eren only looks alarmed. “Are you alright?” he says. Guilt’s already filtering into his voice, his face scrunched up with it.

“I’m fine,” Armin assures him, “I wanted to try, remember? It’s like… testing the strength of a knot.”

Eren’s throat bobs. “Well?”

Armin lets out a breathless laugh, even as fresh desire claws at his insides. “Unyielding,” he says. No matter how much he thinks about sitting up, how much he orders himself to, Armin can’t. It isn’t even that his muscles are straining with the effort; they aren’t responding in the first place. “Wow.”

“Is that—good, or?”

“Um. Good, definitely.” Armin feels his face burn. He hadn’t admitted to Eren that he’d _wanted_ to be at his mercy so completely, but his body makes obvious what he can’t bring himself to say. “Really… very good.”

Eren exhales, his shoulders dropping with relief. “That’s great. Yeah.” A shy smile. “I'll keep going, then?”

At least he’s becoming steadily surer of himself. A little bit of encouragement goes a long way, and Eren has always responded well to positive reinforcement. Armin feels no nerves whatsoever now that Eren’s eyes have taken on a familiar look. Raw and needful, but tender all the same; reserved usually for times like this, when they were alone together and the coming dark made such surrender easy.

Eren shifts closer on the bed, leaning down until his lips brush Armin’s ear.

“Touch yourself,” he says, barely above a whisper.

It’s indescribably strange, feeling his arm move of its own accord. The heel of his palm grinds against his crotch. Armin gasps at the pressure—he’s already hard, the stiff heat of his cock startling even under his own hand. It shouldn’t be so surprising with how often he’s imagined this very moment, though _that_ Armin had kept to himself. Admitting this fancy to Eren at all had taken most of his resolve.

Hanji’s experiments with Eren’s coordinate power had been perfectly sound, perfectly innocent. Non-verbal, long distance communication between him and Eren would have been incredibly useful, especially on the battlefield. It was just that they had unintended—er, unexpected—consequences, albeit ones that had taken a little while longer to manifest in Armin’s imagination.

At first it had been simply comforting. Shifting had unsettled him even then (and still does, sometimes), as though his soul had been transplanted into a stranger's body, a mass of unresponsive, unfamiliar flesh. The largeness of it was nigh incomprehensible. Armin would envisage a wagon with a hundred carriages tethered to it in a long, winding snake, an apparatus beyond his flimsy control. But Eren’s voice, or the strange resonance of his voice—for it was less like hearing and more like feeling, Eren’s orders surfacing in his own mind, rumbling in his chest—had shot through the haze of his shifted self like lightning. It had been like sharing a brain. Which could have been invasive and awful, except that it was— _is_ Eren.

The communication was one-way. Eren could choose what thoughts to transmit, what orders to give, but Armin couldn't respond in turn, nor could Eren read his thoughts. Hanji had been a little disappointed at that. Mutual communication would have been better, but for Armin’s purposes it’s more than good enough. When he had realised that the coordinate worked outside of their titan forms, his mind had spun out on this twisted tangent before he could haul it back.

It's not likely Hanji would have considered this application. Hell, what they're doing would probably be considered misconduct, or at least misappropriation. As he thinks it, Armin's hand snaps open the fastening of his trousers and tugs them off. He almost laughs, more at the absurdity than with any real humour, but the sensation of his fingers sliding beneath the band of his underwear, circling the base of his cock—his own grip, though under Eren’s silent control—has Armin moan instead when he opens his mouth.

“You can’t do anything, can you,” Eren murmurs. He dips one hand under Armin’s shirt. “Not unless I say so.”

His fingertips trace the rise of his left hipbone, then the right. In travelling across his abdomen, Eren skirts deliberately close to his cock, teasing, kneading gently as if to learn the shape of him by touch alone. His wrist brushes Armin’s as it passes down to his waistband. That alone makes his toes curl, uneasy anticipation tangling up with the familiar sense of Eren there.

Armin sucks in a lungful of air, releases it. Slow, steady. He trusts Eren. A bruising trust, to offer up his control so willingly... but Armin is safe, because it's Eren he's offering it to, and they're together in his room (warm, dark) in HQ, and Eren's breathing is a rhythm Armin would recognise even if he were blindfolded.

Eren swallows. His mouth must be dry. His gaze is probing, intense, as if he means to catalogue every part of Armin laid out before him. Such transparent hunger, shown without fear, without shame. Armin used to cringe beneath it, the tenderness of Eren's gaze stripping layers off him as though they were no more than wet paper. Now Armin knows that if the roles were reversed, he'd be the same. Struck dumb with a lover's hopeless look.

The drag of Eren’s fingertips past his navel, through the fine fleece of hairs there, would make Armin squirm if he could. Eren removes his briefs with deliberate slowness. The friction of the fabric, inch by inch, is a cruel tease. Crueller still when Eren speaks.

“Put your arms back on the bed. And don’t move,” comes the command, and Armin complies immediately. Eren’s weight dips the mattress as he swings a leg over Armin’s waist, clothed thigh brushing his erection. The idea of rutting up into him, hot flesh against coarse cotton, is tempting but impossible. Not that he doesn't try—the urge for sweet friction is irresistible, involuntary—but his hips don't lift even a little. A frustrated noise catches in Armin's throat.

Eren hums thoughtfully. He grabs a fistful of the Armin’s shirt collar, hoisting him up so that their lips barely touch.

And when he speaks, they do. Eren's soft mouth grazes Armin's own. “Kiss me,” Eren says, and it is so gentle that Armin aches to obey. He cranes upward to bridge the minute gap between them. Teeth tug at his bottom lip, and then Eren is coaxing Armin’s tongue into his mouth. The kiss is slow, languid, thorough enough to rob Armin of sense.

When they break apart, Eren’s expression is lit up with some new affection. Armin can’t stop himself from smiling at the look of him.

“You didn’t have to order me to do that,” Armin says. In a momentary break of character, Eren laughs.

“But that would defeat the point, right?” he says, almost sheepish. Eren shifts back on his knees and clears his throat. The amusement in his face shifts, too, and in its place something darker surfaces, his voice dropping low again. “Take your shirt off.”

Heat floods Armin’s stomach as he obeys. There’s none of the fumbling he expects: just quick, coordinated movement as he strips off. Another upside of not controlling his own body, Armin thinks wryly.

Eren moves out of reach—not that Armin would be allowed to reach him anyway—and then off the bed altogether. Armin frowns before he realises what Eren is searching for at the bedside table. With brisk efficiency he strides to the foot of the bed and tosses the bottle to land near Armin’s hip.

“Prepare yourself.” As Armin’s hand closes around the bottle of lubricant, he goes on, “Two fingers for now. Lift your hips so I can see.”

It’s not like he hasn’t fingered himself before: sometimes in the dead of night, levered over Eren's lap, Armin would take matters into his own hands quite literally. But that had always been perfunctory, more private, Eren's attention elsewhere as he did so. Doing it like this, making a show of it, is new. Not humiliating necessarily, but a hot prickling sensation lifts the hairs of his arms at the command. Still, where Armin is shy of it, his body isn’t; though he can see and feel the oil pouring into his palm, he jumps when two slick fingers press against him. His hips cant upwards, unthinking, compliant.

With the space between them, he barely catches the noise of Eren’s breath hissing through his teeth. Armin turns his face away, against the bed, overwhelmed with feeling. The sheets are cool against his hot cheek. His fingers twist inside him. In, out, a rhythm in step with his thudding pulse.

“Look at me,” Eren orders. Despite his authoritative tone, Armin can hear the faint tremor of arousal beneath it. He’s trying to look unaffected, but his gaze keeps flicking from Armin’s face to between his legs, eyes glassy. “Three fingers. Faster, this time.”

It doesn’t even feel like it’s his own hand. It’s less gentle than Armin would be, less slow—more the quick, thorough way Eren would finger him. Eren, fucking him by proxy. The thought startles a keening cry from him, especially when his fingers crook just so. His heart jumps, pulsing in his temples, his thighs, his belly, imagining Eren's hand on his despite the distance, imagining the way he must look spreading himself open.

Eren must notice his desperation, because he’s back on the bed in an instant. He glances at Armin’s cock, precum leaking on to his stomach. “Do you think you could come from just that?” Eren asks. “Without anything here, even?”

His hand flattens against Armin’s erection. The new heat of Eren’s palm at his straining sex coaxes a low, needy noise from his chest. Want courses through Armin’s blood, a helpless torrent. Something in his head cuts through the haze, urges him to answer. Maybe that’s Eren, too, and that has Armin biting back another moan. “… I don’t know,” he says, not without effort. His fingers press hard at his prostate, unrelenting. “ _God_ , yes, maybe.”

Eren’s mouth is at his ear again, shallow breaths fanning across his cheek. “I won’t let you,” he whispers, low and fierce. Armin almost sobs, his body tensing, a wonderful edge rolling over him but then away. His fingers stop moving, and though Eren’s hand is so close, Armin can’t bring himself to grind up into it.

A laugh rumbles against the shell of his ear.

“Well done,” Eren says. He moves his hand away, but not before running it up the length of his cock, a scant teasing pressure. “Very obedient.”

For someone who had been so unsure earlier, Eren’s certainly enjoying himself now. He drags his fingers through the precum pooling around Armin’s navel, almost playful. He’s close. So damn close, and all Armin can feel are his own fingers inside him up to the knuckle, unmoving, his stomach flipping at Eren’s persistent yet gentle touch. A hoarse and broken moan escapes him as Eren presses a kiss to the slope of his brow bone. 

“Eren,” Armin says, helpless, hopeless, “please.”

Eren hums a soft acknowledging noise. Armin watches as he kneels on the bed, yanking open his fly. Here his impatience becomes apparent; he shoves his trousers and underwear out of the way just enough to free his cock. His erection looks as painful as Armin’s, though when Eren touches himself he’s slow, much slower than his usual pace. It’s only when Armin realises he can’t look away that he understands. This is Eren showing off, and he's making dead sure that Armin pays attention.

Eventually, blessedly, he stops after a few more lazy strokes, and positions himself between Armin’s thighs. But he doesn’t drive forward like Armin expects—like he wants, his arousal so intense it could scorch flesh. Instead Eren settles back on his haunches. 

“Sit here,” he says, gesturing, and Armin’s body reacts in an instant. The bed creaks as he lurches upright. Eren’s hand slides to the small of his back, encouraging Armin on to his lap.

Face to face like this, Armin is filled with silly sentimentality. Meeting Eren’s eyes, feeling his breathless gasp—surprised at their closeness despite the command he’d just given, as though he can hardly believe his luck.

“Thank you,” Armin says quietly.

He almost expects to not be able to say it, but then Eren would never silence him. Knowing that simple truth makes Armin’s heart swell again. His love for Eren has always made him feel small, and its vastness only ever reveals itself in these moments. It can’t be healthy. Hell, it’s downright dangerous. But the awful, wonderful, hungry enormity of it washes away all of Armin’s uncertainty. Caught in the strength of its undertow, little else matters; it wears away at Armin’s fear until it seems like nothing at all, sharp glass worn to a smooth and frosted pebble in the centre of his palm.

Eren swallows, his gaze diverting. Bashful at Armin’s gratitude, even like this, even after his cool confidence. Armin can’t help but smile at the contrast.

“You’re ready,” Eren says, and though it’s a statement Armin can hear the hesitant question: _are you ready?_ One of Eren’s hands drops from his waist, two fingers pressing in against him.

Armin gives the smallest nod he can. It’s not permission—after all, Eren is in control here—but only after seeing it does Eren pull Armin down on to his lap. The suddenness of it steals Armin’s breath, his mouth falling open in a wordless gasp. It’s not that it hurts much at all, but Eren’s cock fills him so completely, so perfectly that it’s all he can do. Pleasure grinds inside him, scrambles his thoughts. Then, through the sweet confusion he feels Eren’s command, this one unspoken but loud and clear in his mind.

_Move. Fuck yourself._

Eren probably wouldn’t be able to say it aloud, so it’s a good thing he doesn’t need to. Armin should blush at hearing—thinking?—feeling the words, but all it does is clench the hard knot in his belly, his erection throbbing, as though Eren has reached inside of him and pulled all his nerves together in a searing bundle.

It’s almost a relief that he can surrender his body to Eren’s coordinate ability. The muscles of his thighs ache as he lifts himself off Eren’s lap, feeling just the head of his cock tug against him before he sinks down again. Sometimes the effort makes him breathless; at others he can’t help but cry out, the pain and the pleasure together anchoring him close to the edge but never taking him over it.

“Please, Eren,” he manages through the frantic stream of his thoughts. Armin’s not sure what he says aloud and what’s only in his head. “Hah, I—I can’t—”

He wants to touch himself so badly. His cock aches, the pleasure so sharp that it pierces Armin’s brain like a needle. It rubs against Eren’s stomach when he rocks upward, but that slick glancing contact only makes the absence of Eren’s hand there keener still. Though as he thinks it, Eren’s voice, dark and delicious, cuts across his thoughts.

“You’re not going to touch yourself,” he says with certainty, even though he sounds hoarse, breathless, “and I’m not going to touch you. You’re going to come when I tell you to, from this alone. From fucking yourself on me.”

Oh, _god_. Armin’s mind shutters itself, Eren’s words—spoken so openly, brutally—ripping him open. He feels dismantled, helpless. The only thing keeping him together is the singularity of Eren’s focus, his order relentless through the fog of Armin’s arousal. It feels good, though, to give in, letting Eren's power wash over and into him.

He can’t answer Eren anymore anyway. His hands clutch at Eren’s back, and he can’t tell whether that’s his own reaction or one Eren gives him. It must hurt, because Armin can feel his nails scoring marks into the thick muscle of his shoulders. But he doesn’t have the sense of mind to stop and Eren makes no effort to.

“That’s it,” Eren gasps, “there, right? _There_.” He’s thrusting up to meet him now, the urgent rise of his hips when Armin lifts away, Eren’s cock hardly sliding out at all before he drives back in. The muscles in Armin’s legs, his abdomen, his back, burn like sweet fire.

Finally—whether out of mercy or his own desire—Eren pitches forward. Armin hits the mattress, and the impact, the shock of it, Eren’s cock seated inside—Armin can’t hold back his strangled shout. Full, he’s so _full_ , and the swollen weight of his cock shoved between him and Eren is like hot iron against his belly. Eren fucks him deep, so deep it almost hurts. Armin can’t sense his thoughts any longer. He can hardly manage his own, his mind yielding to static white heat. He can feel it coming, the release building, so close that he could almost reach for it. But not yet. Not yet. Armin’s body waits.

Eren stops, his cock buried to the hilt inside him, their bodies flush together that not even sweat could form between the surface of their skin. His hair’s fallen over his face, and through it his eyes are fever bright, nearly black. It gives Eren a wild look. Armin finds him so fiercely beautiful in that moment that he cannot breathe.

“Now,” Eren whispers.

The orgasm tears through him. Every muscle in his body seizes, thighs clamping around Eren’s waist even as he bucks Armin's weight with the vicious force of his thrusts. At first Armin is jarred into silence by the intensity of it, but now a sob rips from his throat, hoarse, painful, as he throws his head back. Even in the comedown he’s gripped by spasms so powerful that Armin almost cramps with them.

The aftermath could last a minute or five. Armin can hardly think, even with the new clarity of release. The strength of it breaks him open; he feels used up but in a good way—as after a long day spent training, a good meal and a hot bath. His bones have gone to rubber. The only thing keeping his knees suspended are Eren’s hands holding firm beneath them.

He lifts his weary gaze upwards. Eren, watching him silently, some powerful emotion showing in his face. Pure wonder.

“God, Armin,” he breathes, and Armin notices then that during his orgasm, Eren must have come too. He can feel the heat of Eren's release inside him now in the quiet calm of the afterglow, his own come cooling on his stomach in tacky streaks.

Armin summons the energy to speak from somewhere deep within. “Yeah. I… I know.”

It’s not exactly eloquent. Armin’s not even sure what he means when he says it. But Eren appears to understand him well enough, and he offers Armin a shaky, sympathetic grin. The sensation of him pulling out makes Armin’s softening cock twitch against his belly.

He's torn the bedsheet clear off both corners; Armin can tell by the way it bunches beneath them, but he's too exhausted to care. Sleep tugs at him. Armin has to fight the urge to close his eyes as Eren lies at his side. Instinct turns him towards the cradle of his body, Eren's weight dipping the mattress just enough that it’s irresistible to sink in against his chest. Eren murmurs a wordless sound, soft, appreciative. As he had earlier, he reaches for Armin’s hands, lax in the scant space between them, and laces their fingers together. It’s such an innocent gesture, so familiar from childhood that Armin’s chest aches. Their palms pressed fully together, matching pairs.

“I don’t think we can do that again,” Eren says sombrely.

“What? What makes you say that?” Armin says, and even in his post-orgasm haze he’s afraid that he’s pushed Eren too far; that in his own selfish pleasure he missed some discomfort. The fear of it is like cold water.

But then, Eren is smiling. His expression is bright, tender, so pleased it could glow in the half-dark. “I think if we did it again, it might ruin you.” He huffs out a shivering laugh. “I don’t think I’ve seen you come as hard as that before. Nor so long. Watching that alone nearly killed _me_.”

Armin’s amazed his blood can travel at all, but some still rushes to his cheeks. It’s true, though; Armin can’t remember the last time he felt quite so wrung out. 

“I don’t think that's a reason to avoid doing it again. The opposite, in fact. But it's true that I might very well black out,” Armin says, and hears in his own voice his weary fondness.

It’s funny how the more tired he is, the more certain he is of his feelings. A curious knowledge but sure as bedrock—that he could love no other soul as much as he loves Eren’s. It still startles him sometimes, the unfathomable extent of it. Like opening an old box and finding some forgotten thing there much larger than you remember when you put it away.

“Maybe we’ll need to start doing risk assessments beforehand,” Eren muses. “It won’t do for you to faint during a training exercise.”

Armin lets out a startled laugh. “Is that what we’re labelling this, then?”

“It was a pretty useful way to develop my skills with the coordinate.” He quirks an eyebrow as if serious, but Armin knows the wry turn of his mouth, a miniscule twitch as he holds back the full force of his smile. “Do you disagree? Wasn’t that why you suggested this in the first place?”

Armin blushes darker at the memory of his bold proposal. And Eren’s honest reaction—his mouth going slack, confusion warring with willing interest. It had not taken much explanation at all for Eren’s eyes to darken. His hesitation had been more concern for Armin’s safety, as unnecessary as Armin had insisted that was, but the idea had taken root by then. The greater challenge had been finding the time to be alone, so busy were they now. 

“I won’t say otherwise if you don’t,” Armin cedes, and he leans in to hide his amusement against Eren’s mouth. The kiss is sweet, slow. One of Eren’s hands rests at the nape of his neck, tracing shapes into the soft lunette of skin above his spine.

That drowsy warmth, helped along by Eren’s soothing touch, drifts over him again. The silence is warm, comfortable; even Armin's mind is at peace. It may be that he has no right to feel so calm, nor so happy. Certainly not when he considers all that looms ahead of them. But with Eren, in the sanctuary of his embrace, the scent of him rising off Armin’s skin like mist on a cold morning, he can’t bring himself to care.

Such selfishness must be a sin. Well, so be it. Some sins are worth the punishment. Armin curls into Eren’s open arms, tucks his head beneath his chin, and turns out his light.


End file.
